> First off, we are aware that interactable isn't a real word. The correct form is interactive but this has connotation that isn't necessarily related to physical interactions.

Interactable would be the nouned form of interactive, so I think it's a reasonable term to use. I dunno if 'physics engine' is the right term for it, though.

What's the main motivation for this kind of stretch-and-squash animation in UIs? Just discoverability for touchscreen UI elements, and to look cool?

In the talk the swipe Down to update with a bounce is modeled as a spring so physics engine is the right word.

Modeling a single spring is a lot different from Box2D, though. It may be the right word, but it might cause a lot of confusion.

Why are rigid bodies special? Hell, look at Nvidia's PhysX, tons of multi-physics in there.

Physics based, maybe. A physics engine generally simulates the behaviour and interactions of a number of physically modeled entities. If it doesn't simulate collisions I wouldn't count it as a physics engine the way that term is typically used.

> Interactable would be the nouned form of interactive, so I think it's a reasonable term to use.

It's close to 'intractable' though, which is how I (mis-)read it.

(Aside: is 'nouned' the verbed form of noun? ;))

>What's the main motivation for this kind of stretch-and-squash animation in UIs?

It has a lot to do with maintaining a "native" feel to your app. Apple uses a lot of these UI patterns in their default apps.

> At some point, UIKit Dynamics was dropped in favor of a home-brewed physics implementation in order to provide more control over the behaviors.

That's pretty cool! Poking around I couldn't find the details of what they cooked up, anyone know more information?

They presented at React Con today, the video should be posted after the conference

Just tested it on an Android device and the performance is amazing. Congrats!

https://play.google.com/store/apps/details?id=com.wix.intera...

This is not a physics engine. It's a springy/ease-friendly ui engine.

I got so excited for a minute! This is still pretty cool though.

Thanks—we changed the title to what the page says.